The original appears to have been drawn with a brush, but be careful how faithfully you copy it. Disney is quick to call the lawyers when anybody comes even close to infringing on their intellectual property.

The signature bears little resemblance to his actual signature and was probably created by his staff, which was mostly animators, so they probably used the same brushes they used in their work. (Or it was drawn to resemble that look.)

That doesn't mean you're okay. I used to be involved with a gaming fan site (not Disney) and the game company had strict rules about what fans could legally post. Companies don't like to offend fans but they need to protect their assets.

It's possible that Disney has posted somewhere their rules regarding fan use of their images, copycat fonts, etc. Also some fan sites may have discussions of what Disney allows.